Many modern electronic devices employ authentication techniques that involve entry of information by a user, such as a personal identification number (PIN) (e.g., typically a four digit number) or a password (e.g., a series of alphanumeric characters). PIN codes and passwords are difficult to remember, especially after a prolonged period of non-use or recently after changing the code or password. Also, information that is entered using a touch screen interface or a keyboard may be learned and used in an unauthorized manner by another party.
Another authentication approach is to use biometric scanning, such as fingerprint detection. But conventional fingerprint scanners can take up valuable space on the surface of an electronic device. In the case of mobile electronic devices, such as mobile telephones, the incorporation of a fingerprint scanner can take away from an area that could otherwise be used for a display.